When Google Ads Goes Off the Rails: The Smart Bidding Doom Spiral and What Caused It
If you've ever seen your Google Ads campaigns inexplicably tank, despite strong CTRs and what looks like a solid setup, you're not alone.
One of the most overlooked causes of campaign failure is incorrect or incomplete conversion tracking. Especially when it comes to offline conversions like phone calls
.
Let’s talk about how to avoid the dreaded Smart Bidding doom spiral using offline conversion tracking with tools like HubSpot and Infinity Call Tracking.
The Doom Spiral Explained
Google's Smart Bidding relies on accurate conversion signals to optimise effectively. But what happens when the conversions it's seeing are junk?
That’s exactly what happened in a campaign I was working on.
We had Infinity Call Tracking set up to capture phone leads and HubSpot as the CRM. The campaign was set to optimise toward qualified leads. Once a lead was marked MQL or SQL in HubSpot, that was passed back to Google as the “real” conversion.
But Infinity calls were also set as a primary conversion. At first, this wasn’t a problem. The volume of Infinity-tracked calls was low, and they weren’t being qualified or optimised toward.
Then it flipped.
At some point, Google realised it was easier to get an Infinity call than a HubSpot qualified lead. So the algorithm started optimising toward Infinity calls, very aggressively.
The problem? These weren’t just poor quality leads. They weren’t leads at all.
Calls to the wrong business. Competitor traffic. Misdials. All of them were counted as conversions. And because Google thought they were winning, it doubled down – shifting spend, raising CPCs, and tanking real lead generation.
Eventually, all the HubSpot-qualified leads dried up. The campaign died.
How to Prevent This With Offline Conversion Tracking
Smart Bidding only works with clean, validated data. That’s where offline conversion tracking (OCT) comes in.
Here’s how to fix it using HubSpot + Infinity:
Step 1: Qualify the lead in HubSpot
Use HubSpot’s native connector to push conversions to Google once a lead is marked MQL/SQL. Keep the form fill as a secondary conversion.
Step 2: Qualify Infinity calls manually
Set Infinity calls to secondary and only upload them as conversions after review. You can export call data (including GCLID) and import it to Google via Google Sheets. Use Notebook LM or Gemini in AI studio to listen to the calls and score them.
Infinity does offer an AI-based lead scoring add-on which could be more useful if you have a high volume of calls.
Step 3: If you use a different CRM
Make sure you're capturing GCLIDs and pushing them into your CRM. I’ve used Zapier for this before but for small uploads with some semi-manual work a Google Sheet upload is better.
What Happens Without It
If you skip qualified conversion tracking, you’re telling Google to optimise on bad or at best, unqualified data.
Eventually the system veers off course, targeting junk leads, irrelevant keywords, and wasting spend. And once it hits a doom spiral, the recovery is impossible.
Pmax Lead Gen is Even Worse
If you're running Performance Max for lead generation, it's even more important to qualify every lead. PMax campaigns are brilliant at volume but without proper offline conversion tracking, you’re going to be drowning in spam, job seekers, bots, and unqualified junk.
The system doesn’t know the difference between a real lead, someone clicking through a Gmail ad just to poke around or Facebook arbitrages who send you junk traffic. If you've ever had a load of people ask you for jobs on a lead gen campaign, you will understand this!
If you don’t close the loop, Smart Bidding will optimise for the wrong outcomes faster than ever.
Final Thought
Smart Bidding is powerful. But only if you teach it what success actually looks like.
Infinity and HubSpot are great tools. But if you don’t close the loop with Google Ads using offline conversion tracking, you risk paying for noise and letting the algorithm bury your campaign in the process.
Don’t let junk data drive your strategy. Train the machine.
Ben has a BEng (Hons) in Computer Science and 20 years of experience in online marketing, specialising in SEO, lead generation and affiliate marketing. After spending over a decade as an igaming affiliate, he has decided to concentrate on GA4 training and SEO Audits.
